Tar Formation and Removal In Biomass … Technologies Conference 30 October 2012 • Pressure • 23‐45 psia • Temperature • Up to 400 F • AllowableTar From Babcock and Wilcox

ober 2012

TAR FORMATION AND REMOVAL IN BIOMASS GASIFICATION TO POWER PROJECTS

STICKY BUSINESS

30 Octo

ANTHONY F. BLACK

30 October 2012Gasification Technologies Conference

“The typical project starts with new ideas, announcements at meetings, construction of the new gasifier. Then it is found that the gas contains 0.110% ‘tars.’ The rest of the time and money is spent trying to solve this problem Most of the gasifier projects thenproblem. Most of the gasifier projects then quietly disappear.”

2Tom Reed (Reference 1)Pictures from ECN

AGENDA

Black & Veatch and Biomass GasificationTar FormationTar RequirementsFrom A to BConclusions

3

BIOMASS GASIFICATION EXPERIENCE ATEXPERIENCE AT BLACK & VEATCHBLACK & VEATCH

4

HISTORY OF BIOMASS GASIFICATION WORK


HISTORY OF BIOMASS GASIFICATION WORK AT BLACK & VEATCH

• AlterNRG ‐ Preliminary Engineering,

SIF

ICATIO

N 2,500 tpd MSW to electricity,

emissions to meet minor source

requirements, air permit application

(2008 2011 N O l LA)

OM

ASS G

AS (2008‐2011, New Orleans, LA)

• Plasco – Independent engineer

for review of Trail Road demonstration

plant (2009‐Present Ottawa Canada)

CH A

ND B

IO plant. (2009‐Present, Ottawa, Canada)

• InEnTec – OE, review FEED design of Fulcrum Bioenergy Plant. (2010, Reno, NV)

• ICM – Due diligence of gasifier technology. (2009‐2010, Wichita, KS)

• EPI – Engineering review and feasibility study of co‐firing syngas in a boiler. (2001‐

ACK &

VEAT EPI Engineering review and feasibility study of co firing syngas in a boiler. (2001

2002, Lincoln, NE)

• Nexterra – Preliminary design of balance of plant and startup assistance. (2008, USC & ORNL)

BLA

5Black & Veatch has a long history of work with biomass gasification technologies.

THE FORMATION OF TAR IN BIOMASS GASIFIERSGASIFIERS

6

MECHANISMS OF TAR FORMATION


• Pyrolysis

MECHANISMS OF TAR FORMATION

• Pyrolysis• Heating of biomass in absence of oxygen

• Final Temperature

• Heating Rate

ON

• Particle Size

• Type and Duration of Quench

R FORM

ATIO Quench

TAR

The species, characteristics, and quantities of tar formed depend on the gasifier process design. 7

TAR TYPES AND QUANTITIES (REFERENCE 1)


TAR TYPES AND QUANTITIES (REFERENCE 1)

• Downdraft

• 0.5 grains/scf• Benzene

• Fluidized

• 5 grains/scf• Benzene

• Updraft

• 50 grains/scf• Benzene

• Phenol

• Cresol

N hth l

• Naphthalene

• Phenanthrene

Fl th

• Toluene

• Acrolein

X l

ON

• Naphthalene

• Acephenanthrene

• Benzopyrene

• Fluoranthene

• Pyrene

• Indene

• Xylene

• Furan

• Fluorene

R FORM

ATIO

• Styrene• Pyrene

• Fluoranthene

TAR Updraft gasifiers tend to produce comparatively more tar than fluidized bed and fluidized bed than downdraft. 8

CLASSIFICATION OF TARS (REFERENCE 2)


CLASSIFICATION OF TARS (REFERENCE 2)

ON

R FORM

ATIO

TAR

The tars of primary concern are Class 5 and some Class 2 and Class 4. 9

ALLOWABLE TAR CONCENTRATIONS IN POWERIN POWER GENERATIONGENERATION EQUIPMENT

10

FUEL FEED TO BOILERS


FUEL FEED TO BOILERS

• Pressure• 23‐45 psia

• Temperature• Temperature• Up to 400 °F

• Allowable Tar

From Babcock and Wilcox

MENTS

Allowable Tar Concentration• 0.2 grains/scf or more

R R

EQUIR

EM

TAR

High allowable fuel feed temperature and low pressure make gas fired boilers tolerant of tars. 11

FUEL FEED TO RECIPROCATING


• Pressure

FUEL FEED TO RECIPROCATING ENGINES

• 75‐120 psia

• Temperature• 32‐140 °F

• Allowable Tar Concentration• 0 05 grains/scf

MENTS

• 0.05 grains/scf

R R

EQUIR

EM

TAR Low fuel feed temperature and moderate fuel feed pressure make the reciprocating engines moderately tolerant of tar. 12

FUEL FEED TO COMBUSTION


FUEL FEED TO COMBUSTION TURBINES

• Pressure• 450‐500 psia

• Temperature• Temperature• 50‐100 °F

• Allowable Tar

MENTS

Allowable Tar Concentration• 0.002 grains/scf

R R

EQUIR

EM

TAR Moderate gas feed temperature and high gas feed pressure make combustion turbines relatively intolerant of tars. 13

FUEL FEED TO FUEL CELLS


• Pressure

FUEL FEED TO FUEL CELLS

Pressure• 30‐500 psia

• Temperature• 90‐1,500 °F

• Allowable Tar Concentration

From NIST

MENTS

Concentration• 0.00005 grains/scf

R R

EQUIR

EM

TAR

Catalyst in the fuel cell requires a very pure fuel. 14

TECHNOLOGIES AVAILABLE FOR REDUCING TARREDUCING TAR CONCENTRATIONSCONCENTRATIONS

15

PRE‐GASIFICATION BIOMASS TREATMENT


PRE GASIFICATION BIOMASS TREATMENT

• Pyrolysis

90 95 t t• 90‐95 percent tar reduction.

• Still need to deal with tars/bio‐oils.

• Torrefaction

OM

A T

O B • 25‐68 percent tar

reduction

FRO

16Gasifying char from pyrolysis or torrefiedproducts reduces tar production.

IN‐SITU REDUCTION


• Quartz• In‐bed catalysts are i ll i d f

IN SITU REDUCTION

• Outlet tar concentration of 2.5‐10 grains/scf.

• Olivine

typically more suited for fluidized bed gasification.

• Olivine• Outlet tar concentration of 1.2‐2.5 grains/scf.

• In‐bed catalysts are more effective in a steam blown

• Dolomite• Difficult converting heavy tars

steam blown environment.

OM

A T

O B

heavy tars.

• Maximum 90 percent reduction.

FRO Olivine and quartz in the bed material can help reduce tar, but additional removal would be necessary 17

POST GASIFICATION REMOVAL


POST GASIFICATION REMOVAL SCRUBBING

OM

A T

O B

FRO

18

Oil scrubbers and venturi scrubbers can achieve less than 0.01 grains/scf tar in the syngas leaving the scrubber.



POST GASIFICATION REMOVALCATALYST

OM

A T

O B

FRO

19

Nickel based tar reformers are capable of converting 9099 percent of the tars in the syngas at a temperature of 1,550 to 1,650 °F.



POST GASIFICATION REMOVALPLASMA

OM

A T

O B

FRO

20Capable of removing greater than 90 percent of naphthalene and about 70 percent of heavy tars.

CONCLUSIONS

21

TAR IS A MANAGEABLE PROBLEM FOR


TAR IS A MANAGEABLE PROBLEM FOR SOME POWER GENERATION TECHNOLOGIES

• Many biomass gasification plants will require more than one

• Acceptable tar concentrations depend on power generation

tar removal technology.

• The gas clean‐up train depends on the end‐use

equipment • 0.002 to 0.2 grains/scf

l depends on the end‐use technology.

• Combustion turbines

• Tar removal technologies have progressed significantly

NCLUSIO

NS and fuel cells are still a

challenge.in the past decade.

CON

22

REFERENCES


REFERENCES

• Reference 1• S. Anis and Z.A. Zainal, “Tar Reduction in Biomass Producer Gas Via Mechanical, Catalytic and Thermal yMethods: A Review,” Renewable and Sustainable Energy Reviews 15 (2011), Pages 2355‐2377

• Reference 2• Reference 2• T.A. Milne, R.J. Evans, and N. Abatzoglou, “Biomass Gasifier ‘Tars’: Their Nature, Formation, and Conversion ” NREL/TP‐570‐25357 November 1998

NCLUSIO

NS Conversion, NREL/TP‐570‐25357, November 1998

CON

23

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Tar Formation and Removal In Biomass … Technologies Conference 30 October 2012 • Pressure • 23‐45 psia • Temperature • Up to 400 F • AllowableTar From Babcock and Wilcox